Quote:
Originally Posted by dcarch
Electric exhaust fans have mostly induction type motors, therefore they will run slower at 50 Hertz. Make sure you have enough CFM.
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With an induction motor fan I can use a small
VFD (an other name for a AC drive). That way I can make the motor run as fast as it can and even control the fan speed based on temperature, if necessary.
Quote:
Originally Posted by dcarch
Generally, 12V fans which can run on solar cells are too low powered to give enough CFM, and unless you have storage batteries, you cannot depend on solar power.
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That may be true, but it just sounds so cool using solar power with a greenhouse. In Finland it may be enough just to open the windows and door of a GH during the day and the fan would need to run only when it is sunny. I can not be sure about the ventilation needs, until I have the GH at the intended place. Fan may be needed also when starting seedlings in a GH and they need to be hardened for winds. With tomato and pepper seedlings I used a 12V fan indoors and when I moved the plants outside, they were much hardier against the moving air outside. Before I started using fan indoors the plants would get damage even in full shade when moved outside first time.
Quote:
Originally Posted by dcarch
So what do the two of you talk about at the dinner table?  |
Guess what our son took to his kindergarten show and tell?
His own multimeter and a 1.5 V battery. He explained the class how to measure, if batteries in toys are still good.
